It's So Cold, Chicago Appears to Be Experiencing 'Frost Quakes'

On the evening of January 30, some Chicagoans were startled by seriously loud noises. It was difficult to pinpoint where they were coming from.

Those noises probably weren't gun shots or fireworks; although it hasn't been confirmed by authorities, it's most likely the people were experiencing a weird phenomenon known as 'frost quakes'.

These booming noises, also known as cryoseisms or ice quakes, are seismic events caused by the sudden freeze and expansion of underground water, which can happen due to a temperature drop.

The expanding ice can split rocks and crack the ground, producing loud noises in the process.

"What we believe is happening is when there is a significant plunge in the air temperature and the saturated soil cools quickly, the ice in the ground can expand rapidly enough to create a loud boom noise at the surface," geologist Steven Battaglia told the Daily Beast.

"Based on the temperature changes in Chicago, it is possible that any areas with saturated ground could have resulted in water expansion and a 'pop' noise near the surface."